The present invention relates to combination type locks and, more specifically, to resettable combination type locks.
Combination type locks for use in securing doors and other entryways have typically used an array of push buttons for entering a preselected access combination to permit unlocking. A typical lock can include, for example, ten push buttons or keys of which a selected subset, for example, four, must be depressed in order to effect unlocking. Prior combination type locks have suffered from a number of disadvantages that have prevented their widespread use. In some lock designs, a particular button can only be used once in a particular access combination. Thus, it is not possible for someone to use the same digit twice. This aspect, of course, limits the total number of access combinations available for the particular lock design. In still other designs, the buttons of a particular access combination need not be pushed in sequence, still further limiting the total number of available access combinations.
While the above-mentioned disadvantages relate to the manner by which combination buttons are made available, in many lock designs the combination lock mechanism is integrated with the door unlatching components so that an overtorquing of the unlatching mechanism will cause damage to the combination setting and controlling components.
Other drawbacks of existing designs relate to the manner in which the access combination is set or reset to effect unlocking. In some locks, the lock must be disassembled and various combination setting plates or other components removed and replaced or repositioned. As can be appreciated, such complexities in reconfiguring the access combination lessens the utility of the lock.